High explosive composition



Sept. 19, 1961 w. E. LAND ETAL 3,000,308

HIGH EXPLOSIVE COMPOSITION Filed March 7, 1956 F I 10 2|5 I I 1 9! -/I I I 2|a I I I I C I I I I I 54 I [III/[WA 7 F1 7 5, 5|

INVENTORS WILLIAM E. LAND RALPH O. FrHlLLlPs 3,000,308 HIGH EXPLOSIVE COMPOSITION William E. Land, Washington, D.C., and Ralph 0.

Phillips, Londonderry, Vt., assignors to the United States of America as represented by the Secretary of the Navy Filed Mar. 7, 1956, Ser. No. 570,194 2 Claims. (Cl. 102-56) This invention relates to high explosive materials and to methods for making and forming such materials and more specifically to the provision of explosive materials which are, before detonation, of increased physical strength so that they may be used as casings for other explosives, as explosives without any other casing, or as explosives with much thinner casing requirements than were hitherto necessary.

At the present time, finely divided aluminum is often mixed with explosives to increase the power of such explosives. We have discovered that the aluminum does not need to be in powdered form, as it has hitherto been used, but can be added to the explosive in relatively thin and narrow ribbons or tapes, or in the form of wires or strands, thereby imparting considerable physical or mechanical strength to the undetonated explosive. Sheet aluminum cut into other shapes, such as honeycombs, rings, or various reinforcing patterns, may be used to give special strength features. Random cut aluminum yarn, ribbon, strands, or wire may be employed in a casting or laminated composition of this explosive in place of the continuous or definite length yarns, ribbons, etc. Where a continuous aluminum yarn, ribbon, strand, or wire is employed, it may be wound on in layers (or a layer) bonded together with an explosive plastic composition either alone or with other filaments or yarns, such as glass yarn, nitrocellulose yarn, nylon, or yarns of different compositions. Also, aluminum woven wire or aluminum wire screening or cloth, or fabric in the form of a glass fiber mat in which aluminum yarn or thread in the required amounts may be incorporated and may be processed in a laminating procedure.

In accordance with the above it becomes possible, for various purposes and desired shapes of the final product, to use the aluminum material in the various aforementioned forms in either a molding or casting process. In these methods of production, as with the rotating mandril or laminating processes more specifically described herein, the aluminum, when included in lengths according to our invention, increases the physical strength of the undetonated high explosive composition, and at the same time, said aluminum enters the detonation chemical reaction of the explosive material with resulting increased explosive power.

It is accordingly an object of this invention to provide aluminum fortified explosive compositions of increased physical strength and methods for their manufacture.

It is a further object of this invention to provide explosive compositions of such improved physical strength characteristics that they may be formed and used as casings for other explosives, or themselves used without a casing or with thinner casings than previously required.

Still another object of this invention is to provide methods whereby explosive materials may be fortified with aluminum in the form of wires, strands, yarn, ribbon, in wire screen cloth and in glass fiber mat type fabric. 7

A still further object of this invention is to provide formed laminated bodies of compositions comprising explosive material coated upon aluminum, the aluminum being in the form of yarn, strands, ribbon, or wire, or being in the form of wire screen or cloth or included in tates Patent G Patented Sept. 19, 1961 glass fiber mat fabric, and to provide methods for the manufacture of such bodies.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a schematic representation of a method, according to the invention, for impregnating or coating aluminum yarn, wire, strands, or ribbon with explosive material and for forming the resulting. material into a given shape;

FIG. 2 is a schematic showing of an enlarged portion of one type of sheet material which may be utilized in the method shown in FIG. 3, namely a glass fiber mat having aluminum strands embedded therein;

FIG. 3 is a schematic representation of a modification of the method illustrated in FIG. 1, showing how the invention may be practiced when the aluminum material is in fabric or sheet form;

FIG. 4 is a side elevation of a sheet material feed roll which may be used in the method of FIG. 3, taken in the direction of the arrows 4-4 of FIG. 3;

FIG. 5 is an enlarged central vertical section of a portion of a bomb casing formed by the method of FIG. 3, the lines 55 of FIG. 3 indicating the section line along which the view is taken;

FIG. 6 is a detail sectional view of a torpedo warhead, illustrating an explosive substance reinforced according to the principle of this invention.

Referring now to the drawings, FIG. 1 is illustrative of one form of the invention in which one or more strands of continuous length aluminum yarn, wire or ribbon, with or without one or more strands of other materials such as glass, nitrocellulose, etc., are fed, as at F, from spools 10, to be treated in accordance with the invention. The various strands may be fed through a gathering means, as at C, and led through a tank 12 containing a bath or slurry of a mixture which comprises an explosive material and a suitable plastic material. The strands are then wound together (or with a desired separation each from the other) on a rotating mandril 14 at a desired angle back and forth over the length of the casing to be formed. Preferably the strands, as they are wound on the form, are more or less parallel to each other but this is not essential. As the strands are wound on the rotating mandril the high explosive mixture, if present in noticeable excess, is squeezed off by any suitable means, as by a scraper or doctor blade 16 which, in turn, is capable of adjustment to exercise a variable bearing on the strands to density and consolidate the structure. A drip tray 18 is employed if and when necessary. The body thus formed is then cured by conventional means compatible with the nature of the plastic materials used, as by the application of heat when a resinous plastic is used, or by mere ambient temperature alone.

In accordance with the general principles discussed hereinabove, explosive material may be combined with lengths of aluminum material in the form of sheet material, as for example, woven wire, screening, cloth or mat containing the desired amount of aluminum material. As a specific example, FIG. 2 illustrates one form of sheet material which may be used, namely a glass fiber mat, in which aluminum yarn or thread 2112 in the required amount is incorporated, as shown, with the glass fibers 21a. Such material may be rolled or wound upon a mandril 32 and the mandril may be in the form of athin aluminum form the exact desired shape of the inside of a bomb casing, in which have been drilled the required number. of holes for the bomb suspension lugs, and this aluminum form remains a part of the bomb case. Prior to rolling the impregnated sheet material thereon, internally threaded adapters 33 are attached at the nose and tail of the casing, such adapters serving to cooperate with means (not shown) to support and rotate the case 32; to supply an opening for filling if it be determined to fill the bomb from an end thereof, and to furnish a place into which to screw the fuze.

Referring now to FIG. 3, the sheet material 21, formed on a roll is fed through a tank 22 containing the desired explosive material-plastic mixture in the form of a slurry 24, the sheet material being suported in the tank on idler rollers 26 and beneath idler rolls 28, as shown. The slurry 24, being in liquid form, coats both sides of the sheet and also penetrates the interstices. The treated sheet material 30 is then rolled onto the mandril or bomb case 32 until the desired wall thickness of the bomb case is arrived at, the mandril 32 being driven to take up the impregnated material. Excess slurry is removed by a scraper blade 34. The pitch of the blade relative to the adjacent surface of the bomb case forms a trough in which the excess slurry collects, the overflow being directed, as at 35, into a drip pan 36. In practice, the scraper blade is supported on a fulcrum and has a regulatable pressure applied to it so that it not only removes excess slurry but serves also to consolidate and compact the difierent layers with a resultant smoother final surface.

As the rolling progresses, the correct ogive shape of the nose and tail is produced by means of doctor blades 40, shown in dotted lines in FIG. 5. The bomb casing after being rolled to its final form is then cured.

In the method of FIG. 3, as above described, the final shape is facilitated by making the original roll 20 of sheet material of a modified barrel cross-section as shown in FIG. 4. This shape is preserved during passage through the vat or tank 22 by supporting the rollers 26 in appropriate positions along a curve similar to that of the sheet whereby the sheet is moved through the slurry bath supported in the desired shape.

It is necessary and preferable to de-oil the surface of the aluminum yarns, ribbons or strands prior to embodiment in the mat of FIG. 2 or prior to immersion directly as in FIG. 1. This is done by immersing the aluminum material in a solution of trisodium phosphate or other suitable grease solvent material that will not only remove the oil but will also etch the surface to a slight extent so that it has a matte finish. In some instances it may be an advantage to further treat the aluminum yarn with a very thin film of latex casein or equivalent bonding material to add strength to the resulting structure through interfacial adhesion.

The term aluminum has broadly been applied to tapes, yarn, strands, etc., of material which can be used to practice the methods of this invention to produce the novel articles made thereby. It is to be understood that the expression aluminum material is intended to include aluminum alloys, such as aluminum-magnesium and other metals alloyed with aluminum to give strength, lightness, or other advantageous qualities.

It should be obvious from the above that the instant invention is concerned primarily with the nature of the combination of the aluminum containing material with high explosive materials and with the manner of efiecting the combination. In the broadest applications of the practice of the invention, it is therefore only necessary that the explosive mixture slurry be comprised of materials capable of adhering to the aluminum material in the forms used herein and capable of being cured to retain the shape into which it is formed. Many such mixtures are well known in the art, and any one of a fairly large number of slurries of explosive substances may be employed, there being nothing new in the slurry itself. Use can be made of any solid explosive, such as TNT, RDX, PETN, I-IMX, etc., compounded with a plastic binder such as styrene-modified polyester which is a heat hardenable liquid. A plasticizer such as dioctylphthalate may be added. The two substances are mixed at room temperature so that a slurry is made of the explosive and the plastic binder. In order to permit polymerization, a catalyst, such as benzoyl peroxide may be added to the slurry. This is a usual procedure in the plastics art, and the slurries so formed are examples of explosive mixtures which can be used in the tanks 12 and 22 in the foregoing methods. In the event it is desired to omit said tanks, the addition could be made to the trough formed between the doctor blades 16, 34 and the explosive casing.

As indicated above, the plastic bonded explosive can be made of a wide variety of known materials. For example, one family of such materials may be formed by admixture of approximately RDX and approximately 20% of a mixture of monomers and/ or polymers and said mixture of monomers and/or polymers may be plasticized by use of a conventional plasticizer if desired. As a more specific example the explosive material may comprise a mixture of 80% RDX and 20% of a polyester (e.g. polystyrene modified polyester) admixed with a plasticizer (e.g. dioctylphthalate).

Reference is made to FIG. 6, which illustrates the use of a casting technique, according to this invention, to produce a cast explosive which, irrespective of being confined in a casing, can be made to rely on its own physical characteristics for support Within said casing to inhibit chipping of the explosive, and which is adapted specifically for use in warheads of various sorts such as in torpedoes, mines, etc. The warhead 50 of the torpedo 51 is shown to contain the foregoing explosive in cast form, now designated 52. Experience has demonstrated that at times portions of the explosive have broken off, only to rattle around loose in the warhead cavity thus introducing the possibility of unbalancing the torpedo. In order to prevent the contingency of said breaking off of explosive fragments, it is proposed to embody reinforcements 54in the casting.

These reinforcements, shown in random form in the drawing, are to be regarded as consisting of aluminum strands, tapes, wires or cloth, either in continuous form or cut into definite lengths, or indefinite lengths, to compose a heterogeneous content. Said reinforcements can be pushed into the Warhead cavity before pouring in the molten explosive, or they can be crammed into the molten explosive after pouring, all to the end of forming a unitary casting after hardening and from which fragments are not likely to break olf.

Mention has also been made hereinbefore of reinforcement by means of a variety of filaments or yarns. In addition to the glass and other filaments premised herein, the principle is expanded to include wires of steel or steel alloy, filaments of cotton, nitrated cotton, polyester or other fiber with the aluminum to produce improved structural and/ or explosive properties.

The description of FIGS. 1 and 3 is predicated on the use of tanks 12 and 22 to contain the impregnating slurry, and of scraper blades 16 and 34 to remove any possible excess. A modification of these arrangements contemplated herein is to omit the tanks 12 and 22 and to convert the blades 16 and 34 into the outer components of troughs. These blades stand at a pitch against the respective mandrils 14 and 32 to complete troughs into which the explosive slurry is poured.

The strands, filaments, sheets, etc., are started around the mandrils and under the blades, whereupon the slurry is poured in and the coating proceeds from there on. It is necessary to make a provision for the outward yielding of the blades as the winding enlarges, thus to make the trough adaptable to the explosive casing as it grows in size.

Referring to FIG. 3, the mandril 32 illustrated therein may take forms other than the thin aluminum form previously described and may consist of either an inert plastic material or of the approximate composition of the final explosive plastic case itself in order to add to the over-all explosive power of the resultant casing.

It should be apparent from the foregoing that the instant invention provides new and useful methods for effecting fortification of explosive mixtures by incorporating aluminum materials therein in such a manner as to augment the physical strength characteristics of the product. Moreover, it should be evident that new and useful articles of manufacture in the nature of bomb casings of light, strong, laminar or cast explosive construction are provided by practice of said new methods.

Obviously, many modifications and variations of this invention are possible in the light of the above teachings. It is therefore to be understood that the invention is not intended to be limited to the specific modification herein illustrated and discussed; its scope being defined by the appended claims.

What is claimed is:

1. A substantially cylindrical hollow explosive bomb casing of cured plastic bonded explosive having a plurality of overlying layers of aluminum material embedded therein, said aluminum material consisting of a continuous aluminum strand wound about the longitudinal axis of the bomb casing.

2. A substantially cylindrical hollow explosive bomb casing of cured plastic bonded explosive having a plurality of layers of material embedded therein, said material consisting of a continuous strand wound about the longitudinal axis of the bomb casing, said strand comprising a continuous aluminum yarn.

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